What is the meaning of cc etc in bikes?

1CC=1 Cubic Centimetre
If you have a 50cc 2-stroke motor cycle, you are basically saying that the piston is displacing 50 Cubic Centimetres of air on every rotation of the crank.
CC's can also be expressed in MM (millimetre's). When you express CC's in MM's, you are effectively measuring the volume of displacement. You can try this yourself, by first taking the head of an engine cylinder, blocking off the port holse in th cylinder, placing the piston/crank at BDC(Bottom Dead Centre) and then filling the cylinder with an exact amount of water (basically whatever the CC's are of the engine you're working on). If you're working on a Suzuki RM 125, then you would put 125 millimetres of water in the cylinder, and it would be filled right to the top, without spilling out.